Developmental and Structural Section
Gottschling, Marc .
Systematics and floral ontogeny of Bourreria (Ehretiaceae, Boraginales).
Bourreria comprises approximately 50 species distributed in Central and northern South America and East Africa. As inferred from molecular data using sequences from the First Internal Transcribed Spacer (ITS1), Bourreria is a representative of core Ehretiaceae (Boraginales) and falls into two monophyletic assemblages: a New World clade (approximately 35 species) and an Old World clade (at least 15 species). The New World clade falls into a large-flowered group (corollas up to 4 cm in diameter) and a smaller-flowered group (corollas about 15 mm in diameter). Additionally, two fruit types are present in the New World species, indehiscent drupes (also found in the Old World representatives) and dry schizocarps (unique in Ehretiaceae). Flower and fruit morphology provide additional characters for phylogenetic analyses. Apomorphies of the monophyletic Bourreria are the valvate calyx lobes, an extensive disc, overlapping lamellae on the abaxial surface of the endocarpids (i.e., fruit parts), and an additional sterile chamber in each endocarpid. The internal architecture of the bicarpellate ovary of Bourreria results from the development of several secondary septs, namely apical, basal, and false septs, which are frequently found in Boraginales, but have not been documented in Ehretiaceae so far. The presence of transfer cells and endosperm haustoria confirm the systematic placement of Bourreria in the Primarily Woody Boraginales (i.e., Heliotropiaceae, Cordiaceae, and Ehretiaceae including parasitic Lennoaceae).
1 - Missouri Botanical Garden, Applied Research Department, c/o Ruth Ann Bizoff, PO Box 299, St Louis, Missouri, 63166-0299, USA
Presentation Type: Paper
Location: Alpine A (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 8:30 AM